(PHP 4, PHP 5, PHP 7, PHP 8)
popen — Opens process file pointer
$command, string $mode): resource|false
Opens a pipe to a process executed by forking the command given
by command.
commandThe command
mode
The mode. Either 'r' for reading, or 'w'
for writing.
On Windows, popen() defaults to text mode, i.e. any \n
characters written to or read from the pipe will be translated to \r\n.
If this is not desired, binary mode can be enforced by setting mode
to 'rb' and 'wb', respectively.
Returns a file pointer identical to that returned by fopen(), except that it is unidirectional (may only be used for reading or writing) and must be closed with pclose(). This pointer may be used with fgets(), fgetss(), and fwrite(). When the mode is 'r', the returned file pointer equals to the STDOUT of the command, when the mode is 'w', the returned file pointer equals to the STDIN of the command.
If an error occurs, returns false.
Example #1 popen() example
<?php
$handle = popen("/bin/ls", "r");
?>
If the command to be executed could not be found, a valid resource is returned. This may seem odd, but makes sense; it allows you to access any error message returned by the shell:
Example #2 popen() example
<?php
error_reporting(E_ALL);
/* Add redirection so we can get stderr. */
$handle = popen('/path/to/executable 2>&1', 'r');
echo "'$handle'; " . gettype($handle) . "\n";
$read = fread($handle, 2096);
echo $read;
pclose($handle);
?>
Note:
If you're looking for bi-directional support (two-way), use proc_open().